Recent studies with electrons, positrons and positroniumMichael J. Brunger, David B. Cassidy, Saša Dujko, Dragana Marić, Joan Marler, James P. Sullivan and Juraj FedorEur. Phys. J. D, 74 7 (2020) 158DOI: https://doi.org/10.1140/epjd/e2020-10278-1